a. Field of Invention
This invention pertains to an automated anesthetic delivery apparatus particularly suited for the dental and medical fields, and more particularly to an apparatus and method in which the rate is controlled and maintained automatically until reset or otherwise changed by the operator.
b. Description of the Prior Art
While local anesthetics eliminate the often excruciating pain that would otherwise be suffered during medical procedures, dental extractions, drilling, etc., the medical and dental patient is still subject to pain from the hypodermic injection of the anesthetic into the local tissues of the body.
It is well established that more than 50% of adult patients fear injections in general, and even a greater number especially fear injections in the mouth during a dental procedure.
Accordingly, it would be desirable to provide a medical and dental anesthetic injection delivery system which substantially eliminates the pain suffered by a patient during injection of anesthetic into the mouth or other tissues of the body.
U.S. Pat. No. 6,022,337, incorporated herein by reference generally describes a local anesthetic delivery system which renders the nerve bundles which supply the teeth and supporting dental structures disabled in the area of the injection and in the path of the needle before a pain sensation is perceived by the patient. The system comprises a drive unit for selectively delivering anesthetic through a controllable handpiece unit which carries a needle for tissue penetration. Operation of the drive unit can be selectively controlled so that different amounts of anesthesia may be delivered through the needle, depending upon whether the practitioner is either penetrating the tissue or has otherwise reached the location within the tissue where nerve disability is required.
The system uses a linear activator to deliver a controlled amount of anesthetic from a cartridge that is locked into the drive unit. The drive unit which can be operated by a foot pedal that is selectively depressed in order to deliver anesthetic through the handpiece unit.
The system is designed to accommodate a local anesthetic cartridge and a variety of needle sizes. The drive unit of the system includes a motor and an on-board microprocessor to facilitate control of anesthetic flow. The drive unit, utilizing the technology described in U.S. Pat. Nos. 4,747,824 and 5,180,371, and incorporated herein by reference, enables delivery of an anesthetic solution at a constant pressure and volume, regardless of variations in tissue resistance. At the delivery end of the needle, the system delivers a minute amount of the anesthetic which precedes the needle during injection in the dental tissue, creating in effect an anesthetic pathway. The combination of an anesthetic pathway and controlled pressure and volume (flow rate) results in an effective and pain-free injection. Importantly, the system further incorporates foot pedal 29 is operatively connected to air hose 31, which in turn is coupled to a pressure sensor 64 located inside unit 13. In operation of system 11, the pressure change from pedal 29 is detected by the sensor 64. Sensor 64 then generates a corresponding control signal used to control the flow of the anesthetic solution. In the preferred embodiment, as described in more detail below, when foot pedal 29 is slightly or partially depressed, system 11 operates at a slow speed. When foot pedal 29 is firmly or fully depressed, system 11 operates at a faster speed. The system can be programmed to have multiple rates of flow, not limited to two speeds.
While this system operates satisfactorily, some physicians or dentists may not be completely satisfied with it because it requires the pedal to be maintained in a certain position for an extended time period.
Accordingly, it is an object of the invention to provide a local anesthetic delivery injection system which can be used for all known medical and dental injection procedures and having an improved automatic mode of operation.
A further objective is to provide a device which reduces the strain on the dentist or other health care practitioner for extended injection sections.
A further objective is to provide an injection device that has an automated mode of operation that allows the physician, dentist or health practitioner to devote his attention to other details and pay attention to the system only when a change in its operation is required.
Yet another object of the invention is to provide a dental anesthetic injection delivery system which enhances the precision and accuracy of anesthetic delivery.
Still other objects and advantages of the invention will in part be obvious, and will in part be apparent from the following description. Briefly, an injection device constructed in accordance with this invention includes an electrically controlled pump, a handle terminating in a needle through which the medication is ejected and a foot switch or other similar control means (i.e., hand control) used to activate the pump controller. The control means may have several positions. In one embodiment, the control means includes three positions: OFF, SPEED 1 and SPEED 2. The pump is off in the off position, at SPEED 1 the medication is administered at a first flow rate, and at SPEED 2 the pain killer is administered at a second, higher flow rate. Alternatively the control means may be adapted to have either many discrete positions or could be adjusted continuously between the SPEED 1 and SPEED 2 positions and the flow rate may be changed substantially continuously between an upper and a lower speed limit. Preferably the control means may be spring loaded or otherwise biased, so that when it is SPEED 1 or SPEED 2 position and is then released, it goes to the OFF position automatically. Importantly, according to this invention, the pump controller is provided with several modes of operation. In one mode of operation, which may be termed a manual mode, the pump controller monitors the position of the control means continuously and operates the pump in a responsive manner so that if the control means is in the SPEED 1 position, the pump is operated at SPEED 1, in the SPEED 2 position, the pump is operated at SPEED 2 (and fluid is delivered at a corresponding rate) and if the control means is in the OFF position, the pump motor is turned off, or it goes into an automatic aspiration mode. Another mode of operation is a so-called cruise control mode. In this mode of operation the pump controller operates in a manner similar to a cruise control in a car. More particularly, in the cruise control mode, when control means is released, the pump controller maintains the previous operation of the pump until a separate control means such as an override switch is activated to change the mode of operation of the pump. This separate control means may consist of a separate push button on the handle, on the controller or on the pedal switch. It may also be achieved as currently embodied via software configuration. A xe2x80x9cwindowxe2x80x9d of time exists in which removal of ones foot from the foot control activates xe2x80x9ccruise-controlxe2x80x9d. This xe2x80x9cwindowxe2x80x9d may be defined within the software and activated by removal of the foot control.
The invention is also applicable to other medical and/or dental devices such as ultrasonic scalers, polishing devices, and other rotary and electronic instruments which are operated by a clinician at a controlled rate or speed.
In one aspect, the invention pertains to an injection device adapted to inject a therapeutic liquid into a patient under the control of a clinician, said device comprising a handle adapted to be held by a clinician for administering the liquid; a pump adapted to selectively deliver the liquid to said handle; a motor adapted to operate said pump at a selected rate in accordance with a control signal; control member operated by the clinician to select said rate, said control member having a first position associated with the selected rate and a second position; and a microprocessor coupled to said control member and adapted to generate said control signal after said control member has been operated and released by the clinician to generate said control signal.